Investigating the Role of Oregano and Cumin Essential Oils in Curbing Aspergillus flavus Growth in Almonds

This study explores the antifungal efficacy of oregano and cumin essential oils against Aspergillus flavus in almonds. Our findings revealed that oregano oil at a concentration of 150 µg l-1 was significantly more effective in inhibiting Aspergillus flavus growth than cumin oil at 300 µg l-1. After a 10-day incubation period, almonds treated with oregano oil exhibited an average fungal infection rate of just 5%, compared to 58% for cumin oil-treated almonds, and a high 95% in untreated control samples. This indicates a remarkable 94% reduction in Aspergillus flavus growth for oregano oil-treated almonds in comparison to the control group. In contrast, cumin oil showed a 39% decrease in fungal contamination relative to the control, demonstrating its lesser but notable antifungal potential. The study also found that almonds with dry peel had lower mold contamination rates than those with green peel when treated with these essential oils, highlighting the protective role of the hardened endocarp. Thirteen panellists rated almond qualities using a 9-point scale. Cumin oil treated almonds had higher aroma and flavor ratings than oregano oil and control almonds. Cumin offered a spicy aroma and harmonious flavor, while oregano had a medicinal aroma and bitter taste. Cumin effectively inhibited fungal growth and maintained almond quality. Sensory analysis showed a consumer preference for the aroma and taste of cumin oil-treated almonds, despite the lower antifungal efficacy. Overall, this research underscores the potential of oregano and cumin essential oils as sustainable alternatives to synthetic preservatives in controlling Aspergillus flavus infection in almonds post-harvest.